David Lowes

Implement squareroot

Implementation of a square root function in JavaScript using Newton's method

var sqrt = function(x) {
  var isGoodEnough = function(guess) {
    return Math.abs(guess * guess - x) / x < 0.001;
  };

  var improve = function(guess) {
    return (guess + x / guess) / 2;
  };

  var sqrIter = function(guess) {
    return (isGoodEnough(guess)) ? guess : sqrIter(improve(guess))
  };

  return sqrIter(1.0);
};



>> sqrt(9)
>> 3.00009155413138